The big-fish-little-pond effect (BFLPE) posits that students with the same ability will have higher academic self-concepts when they are in low-ability classes than in high-ability classes. Our research puts the BFLPE under scrutiny by examining goal orientations as the moderators that may affect the size of the BFLPE. We collected data on mathematics self-concept, mathematics ability and goal orientation from 7334 Hong Kong junior secondary school students in 201 classes. We hypothesised that the BFLPE would be exacerbated for students who endorsed high extrinsic goals while the BFLPE would be attenuated for students who endorsed high intrinsic goals. However, the results did not fully support the hypothesis. We found that students who were highly motivated in general (both intrinsic and extrinsic) experienced stronger BFLPE. The implications of the findings are discussed.